Large PCAP screen with multiple touch controller ASICs with interleaved connections

ABSTRACT

System, method, and computer program product embodiments are provided for a projected capacitive (PCAP) touch system that includes a touchscreen and two or more touch controller application-specific integrated circuits (ASICs) communicatively coupled to the touchscreen, where connections between receiver (and/or driver) circuits of the two or more touch controller ASICs and touchscreen electrodes are interleaved. The two or more touch controller ASICs do not exchange raw mutual capacitance or self capacitance data during a measurement frame. Further, a processor may be coupled to the two or more touch controller ASICs, and may determine final touch coordinates based on all subsets of coarse touch coordinate data from each of the two or more touch controller ASICs. Embodiments also include determining each subset of coarse touch coordinate data based on a shape of a touch rather than a two-dimensional square or rectangular region of the touchscreen.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.15/874,510, filed on Jan. 18, 2018, entitled Large PCAP Screen withMultiple Touch Controller ASICs with Interleaved Receiver Connections,the contents of which are hereby incorporated by reference in itsentirety.

BACKGROUND Field

The present disclosure relates generally to touch sensitive systems, andmore specifically to large scale display systems.

Background Art

The ability to interact with computer applications via touch withdisplays is ubiquitous for today's consumers. While several touchtechnologies are possible to support touch interactions, each hasadvantages and disadvantages that tailor each for particularenvironments, sizes, and applications. Projected capacitive (PCAP)technology is utilized to support characteristics expected from touchinteractions in small screen devices such as handheld devices, e.g.,smartphones, tablets, etc. Translating those characteristics for usewith larger screens and applications faces challenges.

Large PCAP touchscreen systems that include multiple touch controllerapplication-specific integrated circuits (ASICs) to support a largenumber of sensor electrodes result in increased cost and complexity toachieve acceptable response times and touch detection accuracy comparedto smaller PCAP touchscreen systems with a single touch controller ASIC.Further, implementing a single touch controller ASIC that would provideenough sensor input/output (I/O) pins to cover the large number ofsensor electrodes required for a large PCAP touchscreen in the samemanner as a smaller PCAP touchscreen would be cost prohibitive.

SUMMARY

Large projected capacitive (PCAP) touchscreens that include multiplePCAP touch controller application-specific integrated circuits (ASICs)are computationally intensive. For example embodiments discussed herein,references of “ASIC” means a “PCAP touch controller ASIC,” and“electrode” means “touchscreen electrode.” When an ASIC of the multipleASICs that cover a large PCAP touchscreen system, obtains raw touchsignal data from a portion of the large PCAP touchscreen, a dataprocessor needs to merge this ASIC's raw touch signal data with rawtouch signal data from the remaining multiple ASICs before the finaltouch contact locations (e.g., (x,y) coordinates) are processed andderived for the large PCAP touchscreen. The exchanging and merging ofthe raw touch signal data among the multiple ASIC's can becomputationally intensive.

Some embodiments include a PCAP touch system with a large PCAPtouchscreen having a large number of electrodes and multiple ASICs thatavoid the complexity of exchanging and/or merging the raw touch signaldata among the multiple ASICs.

System, method, and computer program product embodiments are providedfor a PCAP touch system that includes a touchscreen and two or moretouch controller application-specific integrated circuits (ASICs)communicatively coupled to the touchscreen, to detect capacitive touchdata from touchscreen electrodes, wherein each receiver circuit of thetwo or more touch controller ASICs connects to a selected portion of thetouchscreen electrodes in an interleaved manner. In some embodiments,the two or more touch controller ASICs do not exchange raw mutualcapacitance data during a measurement frame.

In some embodiments, the one or more processors are configured to:determine a final touch coordinate based on a first subset of coarsetouch coordinate data from a first touch controller ASIC and a secondsubset of coarse touch coordinate data from a second touch controllerASIC. Each subset of coarse touch coordinate data from the first orsecond touch controller ASIC may be based at least on a number ofhorizontal and vertical electrode intersections whose mutual capacitancemeasurements satisfy a significant touch threshold. In addition, a firstsubset of touchscreen electrodes may be odd numbered and a second subsetof touchscreen electrodes may be even numbered, wherein each subset ofcoarse touch coordinate data includes: a partial sum of mutualcapacitance measurements satisfying a significant touch threshold acrosseach subset of touchscreen electrodes; an X touch coordinate associatedwith each subset of touchscreen electrodes; and a Y touch coordinateassociated with each subset of touchscreen electrodes, wherein thepartial sum, X touch coordinate, and Y touch coordinate are calculatedby each touch controller ASIC individually for one of the first subsetor the second subset of touchscreen electrodes without communicatingwith the other touch controller ASIC.

In the PCAP touch system, a coarse pitch size of each subset of coarsetouch coordinate data from one of the two or more touch controller ASICsmay be based on a pitch size of the touchscreen and a number of the twoor more touch controller ASICs. Some embodiments include thirdconnections between driver circuits of the first touch controller ASICand a third subset of touchscreen electrodes of the touchscreen, thatare interleaved with fourth connections, wherein the fourth connectionsare between driver circuits of the second touch controller ASIC and afourth subset of touchscreen electrodes of the touchscreen. The two ormore touch controller ASICs may be configured to determineself-capacitance measurements.

Further embodiments, features, and advantages of the present disclosure,as well as the structure and operation of the various embodiments of thepresent disclosure, are described in detail below with reference to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES

The accompanying drawings, which are incorporated herein and form partof the specification, illustrate the present disclosure and, togetherwith the description, further serve to explain the principles of thedisclosure and to enable a person skilled in the relevant art(s) to makeand use the disclosure.

FIG. 1 illustrates a projected capacitive (PCAP) touch system, accordingto example embodiments of the disclosure.

FIG. 2A and FIG. 2B illustrate an exemplary first electrode pattern thatcan be used to implement the touchscreen according to an exemplaryembodiment of the present disclosure;

FIG. 3A and FIG. 3B illustrate an exemplary second electrode patternthat can be used to implement the touchscreen according to an exemplaryembodiment of the present disclosure;

FIG. 4A illustrates a first exemplary touchscreen according to anexemplary embodiment of the present disclosure;

FIG. 5 illustrates a conceptual circuit for mutual-capacitance readoutmode, according to example embodiments of the disclosure.

FIG. 6 illustrates a schematic representation of a PCAP touchscreen,according to example embodiments of the disclosure.

FIGS. 7A and 7B illustrate operation of the first exemplary touchscreenaccording to an exemplary embodiment of the present disclosure.

FIG. 8 illustrates a modified schematic representation of a PCAPtouchscreen with finger touch signal strengths displayed on touchscreen,according to example embodiments of the disclosure.

FIG. 9 illustrates challenges of a large PCAP touchscreen withinter-ASIC data transfer between two touch controller ASICs used tocontrol the large PCAP touchscreen.

FIG. 10 illustrates challenges of a large PCAP touchscreen withinter-ASIC data transfer between two touch controller ASICs in a timingdiagram.

FIG. 11 illustrates a large PCAP touchscreen controlled by two touchcontroller ASICs with interleaved receiver connections for mutualcapacitance measurements, according to example embodiments of thedisclosure.

FIG. 12 illustrates a portion of a large PCAP touchscreen controlled bytwo touch controller ASICs with interleaved receiver connectionsdisplaying touch signal strengths, according to example embodiments ofthe disclosure.

FIG. 13 illustrates a timing diagram of a large PCAP touchscreencontrolled by two touch controller ASICs with interleaved receiverconnections, according to example embodiments of the disclosure.

FIG. 14 illustrates a large PCAP touchscreen controlled by four touchcontroller ASICs with interleaved receiver connections, according toexample embodiments of the disclosure.

FIG. 15 illustrates a conceptual circuit for self-capacitance readoutmode, according to example embodiments of the disclosure.

FIG. 16 illustrates an example of self-capacitance touch measurements,according to example embodiments of the disclosure.

FIG. 17 illustrates challenges for water rejection algorithms withself-capacitance measurements from a large PCAP touchscreen withinter-ASIC data transfer between two touch controller ASICs.

FIG. 18 illustrates challenges for a large PCAP touchscreen controlledby two touch controller ASICs with interleaved receiver connections forself-capacitance measurements, according to example embodiments of thedisclosure.

FIG. 19 illustrates a large PCAP touchscreen controlled by two touchcontroller ASICs with interleaved receiver connections and interleaveddriver connections for self-capacitance measurements, according toexample embodiments of the disclosure.

FIG. 20 illustrates a timing diagram of a large PCAP touchscreencontrolled by two touch controller ASICs with interleaved receiverconnections and interleaved driver connections, with self-capacitancemeasurements in addition to mutual-capacitance measurements, accordingto example embodiments of the disclosure.

FIG. 21 is an example computer system useful for implementing variousembodiments.

The present disclosure will now be described with reference to theaccompanying drawings. In the drawings, generally, like referencenumbers indicate identical or functionally similar elements.Additionally, generally, the left-most digit(s) of a reference numberidentifies the drawing in which the reference number first appears.

DETAILED DESCRIPTION

The following Detailed Description of the present disclosure refers tothe accompanying drawings that illustrate exemplary embodimentsconsistent with this disclosure. The exemplary embodiments will fullyreveal the general nature of the disclosure that others can, by applyingknowledge of those skilled in relevant art(s), readily modify and/oradapt for various applications such exemplary embodiments, without undueexperimentation, without departing from the spirit and scope of thedisclosure. Therefore, such adaptations and modifications are intendedto be within the meaning and plurality of equivalents of the exemplaryembodiments based upon the teaching and guidance presented herein. It isto be understood that the phraseology or terminology herein is for thepurpose of description and not of limitation, such that the terminologyor phraseology of the present specification is to be interpreted bythose skilled in relevant art(s) in light of the teachings herein.Therefore, the detailed description is not meant to limit the presentdisclosure.

The embodiment(s) described, and references in the specification to “oneembodiment”, “an embodiment”, “an example embodiment”, etc., indicatethat the embodiment(s) described may include a particular feature,structure, or characteristic, but every embodiment may not necessarilyinclude the particular feature, structure, or characteristic. Moreover,such phrases are not necessarily referring to the same embodiment.Further, when a particular feature, structure, or characteristic isdescribed in connection with an embodiment, it is understood that it iswithin the knowledge of one skilled in the art to effect such feature,structure, or characteristic in connection with other embodimentswhether or not explicitly described.

U.S. patent application Ser. No. 15/214,196, entitledProjected-Capacitive(PCAP) Touchscreen filed on Jul. 19, 2016, and U.S.patent application Ser. No. 14/871,496, entitled Supporting MultipleUsers on a Large Scale Projected Capacitive Touchscreen ('496Application) filed on Sep. 30, 2015, are herein incorporated byreference in their entirety. Both of these applications describe PCAPtouchscreen systems.

U.S. patent application Ser. No. 62/508,549, entitled PCAP with EnhancedImmunity to Water Contaminants filed on May 19, 2017, (“ImmunityApplication”) which is incorporated herein by reference in its entirety,includes description of a mixed-mode measurement frame that includesself-mode measurement and a mutual-mode measurement.

FIG. 1 illustrates a projected capacitive (PCAP) touch system 100according to example embodiments of the disclosure. System 100 includestouchscreen 110, circuit board 140, and computing device 130. Inembodiments, touchscreen 110 may be a large scale PCAP touchscreen usedas an interactive table surface. The interactive table surface may be alarge gaming table, a home entertainment system, an industrial controlsystem, a corporate boardroom communication and collaboration device,etc.

Touchscreen 110 may be communicatively coupled to circuit board 140 viainterface 160, and circuit board 140 may be communicatively coupled tocomputing device 130 via interface 170. Interfaces 160 and 170 may bewired or wireless and comprise various technologies including but notlimited to universal serial bus (USB), Bluetooth™ Low Energy (BLE),Wi-Fi™, and/or logic traces on a circuit board that may be coupled to aconnector.

Circuit board 140 may include two or more touchscreen controllerapplication-specific integrated circuits (ASICs) although only 120 a and120 b are depicted. Each touchscreen controller ASIC 120 includes theirrespective firmware 125. Computing device 130 may be a host computerrunning software application 135 (e.g., application-level software),such as a gaming application. Software application 135 may supportmultiple users that interact with software application 135. Touchscreencontrollers ASIC 120 a and 120 b include corresponding firmware 125 thatmay communicate with software application 135 in computing device 130via a communication protocol to support the performance characteristicsof software application 135. The communication between firmware 125 andsoftware application 135 may be indirect via processor 150.

Circuit board 140 may also include processor 150 that may include a USBinterface, for example. Processor 150 may receive coarse touchcoordinate data from each of the touchscreen controller ASICs 120, anduse the received coarse touch coordinate data to calculate final touchcoordinates, for example by linear interpolation or weighted summation.Processor 150 may generate reports that include the final touchcoordinates (e.g., (x,y) coordinates) and transmit the reports tocomputing device 130 via interface 170. Note that there is no exchangeof raw touch signal data (e.g., raw mutual capacitance measurements)between touchscreen controller ASIC 120 a and touchscreen controllerASIC 120 b. Coarse touch coordinate data is different than raw touchsignal data. For example, coarse touch coordinate data may includecompressed and processed high-level information regarding portionedestimates of touch coordinates and portioned touch signal sums aroundtouch center locations from each of the touchscreen controller ASICs 120as described later.

A case may arise ASIC 120 a may provide clock synchronizationinformation to touchscreen controller ASIC 120 b, such as whentouchscreen controller ASIC 120 a is a master device and touchscreencontroller ASIC 120 b is a slave device. Providing clock synchronizationinformation is not the same as exchanging raw touch signal data.Accordingly, processor 150 may be included in the master device,touchscreen controller ASIC 120 a. Thus, touchscreen controller ASIC 120b may transmit coarse touch coordinate data to processor 150 forcombining the coarse touch coordinate data from touchscreen controllerASIC 120 b with coarse touch coordinate data received from touchscreencontroller ASIC 120 a to produce final touch coordinates.

First Exemplary Touchscreen

FIG. 2A and FIG. 2B illustrate an exemplary first electrode pattern 200that can be used to implement touchscreen 110 of FIG. 1, according to anexemplary embodiment of the present disclosure. For explanationpurposes, FIG. 2A and FIG. 2B may be described with elements fromprevious figures. Electrode pattern 200 includes vertical electrodes202.1 through 202.M, configured and arranged in series of M columns, anda plurality of adjacent floating transparent conductive islands disposedon a transparent substrate 204. The transparent substrate 204 representsone or more optically transparent materials. The one or morenon-conductive, optically transparent materials can be flexible orinflexible. In an exemplary embodiment, the transparent substrate 204 isimplemented using a plate of glass.

The vertical electrodes 202.1 through 202.M are oriented in a verticaldirection, such as parallel to the y-axis of the Cartesian coordinatesystem and perpendicular to the x-axis of the Cartesian coordinatesystem. In this configuration and arrangement, the vertical electrodes202.1 through 202.M may be referred to as “X” electrodes due to theirrole in determining the x coordinates of the touch of the operator whenpresent. However, those skilled in the relevant art(s) will recognizethat the other configurations and arrangements for the verticalelectrodes 202.1 through 202.M are possible without departing from thespirit and scope of the present disclosure.

As illustrated in FIG. 2A, the vertical electrodes 202.1 through 202.Minclude electrode pads 206.1.1 through 206.i.M and electrode terminuses208.1.1 through 208.2.M. In an exemplary embodiment, the electrodeterminuses 208.1.1 through 208.2.M represent interfaces between theelectrode pads 206.1.1 through 206.i.M and associated electronics, suchas by using one or more printed silver conductors on the transparentsubstrate 204 and/or one or more flex cables.

As additionally illustrated in FIG. 2A, the electrode pads 206.1.1through 206.i.M are configured and arranged in a series of i rows and aseries of M columns on the transparent substrate 204. Similarly, theelectrode terminuses 208.1.1 through 208.2.M are configured and arrangedin a series of two rows and a series of M columns on the transparentsubstrate 204. Suitable connections between the electrode pads 206.1.1through 206.i.M to corresponding electrode terminuses 208.1.1 through208.2.M form a corresponding vertical electrode from among the verticalelectrodes 202.1 through 202.M. For example, the electrode pads 206.1.1through 206.i.1 within a first column are mechanically and electricallyconnected to the electrode terminuses 208.1.1 through 208.2.1 from amonga first column to form the vertical electrode 202.1. However, thoseskilled in the relevant art(s) will recognize that other groupings ofthe electrode pads 206.1.1 through 206.i.M for one or more of thevertical electrodes 202.1 through 202.M are possible without departingfrom the spirit and scope of the present disclosure.

As shown in FIG. 2A, electrode pads 206.1.1 through 206.i.M can eachhave one or more floating transparent conductive islands adjacent to it.For example, each of electrode pads 206.1.1 through 206.i.M can havefour floating transparent conductive islands 212.1 through 212.aadjacent to it, as illustrated in further detail with respect toelectrode pad 206.1.M−1 located in a portion 210 of electrode pattern200. Although four floating transparent conductive islands 212.1 through212.a are illustrated in FIG. 2A, those skilled in the relevant art(s)will recognize that other numbers of transparent conductive islands arepossible without departing from the spirit and scope of the presentdisclosure. In an exemplary embodiment, the electrode pads 206.1.1through 206.i.M and the plurality of floating transparent conductiveislands can be implemented using a suitable transparent conductor, e.g.,indium-tin-oxide (ITO). Further, although the electrode pads 206.1.1through 206.i.M are implemented in a shape of a diamond in FIG. 2A, itshould be appreciated that this is illustrative and not restrictive ofthe shape that can be implemented by those skilled in the relevantart(s).

As the term ‘floating’ implies, the plurality of floating transparentconductive islands represent shapes of transparent conductive material,which are not electrically connected within the electrodes 202.1 through202.M. In an embodiment, the plurality of floating transparentconductive islands eliminate, or substantially reduce, one or moreoptical discontinuities that would be otherwise present in touchscreen110 that includes electrodes 202.1 through 202.M.

FIG. 2B illustrates a cross-section of the portion 210 of electrodepattern 200 along the line A-A′, and includes a cross-section of thetransparent substrate 204, a cross-section of the electrode pad206.1.M−1, a cross-section of the floating transparent conductive island212.1, and a cross-section of the floating transparent conductive island212.3. In an exemplary embodiment, the transparent substrate 204 isimplemented as a plate of glass with an approximate thickness between afraction of a millimeter to several millimeters, while the electrode pad206.1.M−1, the floating transparent conductive island 212.1, and/or thefloating transparent conductive islands 212.3 is implemented using acoating of ITO with an approximate thickness less than a wavelength oflight.

FIG. 3A and FIG. 3B illustrate an exemplary second electrode pattern 300that can be used to implement touchscreen 110 according to an exemplaryembodiment of the present disclosure. For explanation purposes, FIGS. 3Aand 3B may be described with elements from previous figures. Secondelectrode pattern 300 includes horizontal electrodes 302.1 through302.N, configured and arranged in a series of N rows, and a plurality ofadjacent floating transparent conductive islands disposed on atransparent substrate 304. The transparent substrate 304 issubstantially similar to the transparent substrate 204 and will not bediscussed in further detail. However, those skilled in the relevantart(s) will recognize that the transparent substrate 304 can beimplemented with a different material from the transparent substrate 204without departing from the spirit and scope of the present disclosure.

In the exemplary embodiment illustrated in FIG. 3A, the horizontalelectrodes 302.1 through 302.N are oriented in a horizontal direction,such as perpendicular to the y-axis of the Cartesian coordinate systemand parallel to the x-axis of the Cartesian coordinate system. In thisconfiguration and arrangement, the horizontal electrodes 302.1 through302.N may be referred to as “Y” electrodes due to their role indetermining the y coordinates of the touch of the operator when present.However, those skilled in the relevant art(s) will recognize that theother configurations and arrangements for the electrodes 302.1 through302.N are possible without departing from the spirit and scope of thepresent disclosure.

As illustrated in FIG. 3A, the horizontal electrodes 302.1 through 302.Ninclude electrode pads 306.1.1 through 306.N.q and electrode terminuses308.1.1 through 308.N.2. In an exemplary embodiment, the electrodeterminuses 308.1.1 through 308.N.2 represent interfaces between theelectrode pads 306.1.1 through 306.N.q and associated electronics, suchas by using one or more printed silver conductors on the transparentsubstrate 304 and/or one or more flex cables.

As additionally illustrated in FIG. 3A, the electrode pads 306.1.1through 306.N.q are configured and arranged in a series of N rows and aseries of q columns on the transparent substrate 304. Similarly, theelectrode terminuses 308.1.1 through 308.N.2 are configured and arrangedin a series of N rows and a series of two columns on the transparentsubstrate 304. Suitable connections between the electrode pads andcorresponding electrode terminuses form a corresponding horizontalelectrode. For example, the electrode pads 306.1.1 through 306.1.q aremechanically and electrically connected to the electrode terminuses308.1.1 through 308.1.2 to form the horizontal electrode 302.1. However,those skilled in the relevant art(s) will recognize that other groupingsof the electrode pads 306.1.1 through 306.N.q for one or more of thehorizontal electrodes 302.1 through 302.N are possible without departingfrom the spirit and scope of the present disclosure.

As shown in FIG. 3A, electrode pads 306.1.1 through 306.N.q, can eachhave one or more floating transparent conductive islands adjacent to it.For example, each of electrode pads 306.1.1 through 306.N.q can havefloating transparent conductive islands 312.1 through 312.a and floatingtransparent conductive islands 314 adjacent to it, as illustrated infurther detail with respect to electrode pad 306.2.q located in aportion 310 of electrode pattern 300. In an embodiment, the electrodepads 306.1.1 through 306.N.q and the plurality of floating transparentconductive islands of electrode pattern 300 are substantially similar tothe electrode pads 206.1.1 through 206.i.M and the plurality of floatingtransparent conductive islands of electrode pattern 200, respectively;therefore, only differences are discussed in further detail herein.

FIG. 3B illustrates a cross-section of the portion 310 of electrodepattern 300 along the line B-B′, which includes a cross-section of thetransparent substrate 304, a cross-section of the electrode pad 306.2.q,a cross-section of the floating transparent conductive island 312.1, anda cross-section of the floating transparent conductive island 312.3.

FIG. 4A illustrates a first exemplary touchscreen 400 according to anexemplary embodiment of the present disclosure. For explanationpurposes, FIG. 4A may be described with elements from previous figures.For example, touchscreen 400 may be the same as touchscreen 110. Asillustrated in FIG. 4A, the first electrode pattern 200, illustrated in“light gray,” and the second electrode pattern 300, illustrated in “darkgray,” are overlaid on top of each other to form the touchscreen 400. Inan embodiment, transparent substrates 204 and 304 are attached to eachother (with the electrode patterns 200 and 300 facing each other) withan optically clear adhesive (OCA) to form the touchscreen 400. Asillustrated in FIG. 4A, the vertical electrodes 202.1 through 202.M areplaced side-by-side in a horizontal direction where each successivevertical electrode 202.1 to 202.M has an increasing x coordinate in aCartesian coordinate system to provide an example. Similarly, thehorizontal electrodes 302.1 through 302.N are placed one-above-the-otherin a vertical direction where each successive horizontal electrode 302.1to 302.q has an increasing y coordinate in a Cartesian coordinate systemto provide an example, to form the touchscreen 400. In an exemplaryembodiment, the touchscreen 400 represents a PCAP touchscreen.

FIG. 4A additionally illustrates a portion of the touchscreen 400 infurther detail. As discussed above, the touchscreen 400 is formed byoverlaying electrode patterns 200 and 300 on top of each other. Ideally,when electrode patterns 200 and 300 are overlaid on top of each other, asingle layer of transparent conductive material can be perceived by thehuman eye when viewing the touchscreen 400. However, in some situations,one or more optical discontinuities may be present in the touchscreen400.

As illustrated in FIG. 4A, one or more first regions 402 represent oneor more first optical discontinuities having two or more layers oftransparent conductive material formed by the overlaying of electrodepatterns 200 and 300. For example, the one or more first regions 402result from connections among columns of the electrode pads 206.1.1through 206.i.M (of electrode pattern 200) overlaying correspondingconnections among rows of the electrode pads 306.1.1 through 306.N.q (ofelectrode pattern 300).

As further illustrated in FIG. 4A, one or more second regions 404 and406, illustrated in “white” in FIG. 4A, represent one or more secondoptical discontinuities having no layers of transparent conductivematerial formed by the overlaying of electrode patterns 200 and 300. Theone or more second regions 404 represent regions having no layers oftransparent conductive material at the ends of the floating transparentconductive islands 212.1 through 212.a (of electrode pattern 200) and/orthe floating transparent conductive islands 312.1 through 312.a (ofelectrode pattern 300). Similarly, the one or more second regions 406represent regions having no layers of transparent conductive materialbetween the electrode pads 206.1.1 through 206.i.M and the electrodepads 306.1.1 through 306.N.q and associated floating transparentconductive islands.

Operation of the First Exemplary Touchscreen

FIGS. 7A and 7B illustrate operation of the first exemplary touchscreenaccording to an exemplary embodiment of the present disclosure. Asdiscussed above in FIG. 4A, the first electrode pattern 200, illustratedin “light gray,” and the second electrode pattern 300, illustrated in“dark gray,” are attached to form the touchscreen 400. Although only theoperation of the touchscreen 400 is to be described in FIGS. 7A and 7B,those skilled in the relevant art(s) will recognize that this exemplaryoperation of the touchscreen 400 is likewise applicable to thetouchscreen 110 without departing from the spirit and scope of thepresent disclosure.

The touchscreen 400 can operate in a row scanning mode of operation orin a column scanning mode of operation. In the row scanning mode ofoperation, one or more horizontal electrodes from among the horizontalelectrodes 302.1 through 302.N are sequentially excited by a drivesignal. The drive signal capacitively couples to one or more verticalelectrodes from among the vertical electrodes 202.1 through 202.M.Transferred electrical charges or currents due to mutual capacitance(s)between the driven horizontal electrode and the one or more verticalelectrodes are measured to detect a presence and/or a location of atouch from an operator, such as a finger of the operator, a hand of theoperator, and/or other objects available to the operator, such as astylus to provide an example. Similarly, in the column scanning mode ofoperation, one or more vertical electrodes from among the verticalelectrodes 202.1 through 202.M are sequentially excited by a drivesignal. The drive signal capacitively couples to one or more horizontalelectrodes from among the horizontal electrodes 302.1 through 302.N.Transferred electrical charges or currents due to mutual capacitance(s)between the driven vertical electrode and the one or more horizontalelectrodes are measured to detect a presence and/or a location of atouch from an operator. The description to follow further describes theoperation of the touchscreen 400 in the row scanning mode of operation.Those skilled in the relevant art(s) will recognize that the columnscanning mode of operation operates in a similar manner withoutdeparting from the spirit and scope of the present disclosure.

During the row scanning mode of operation and as further illustrated inFIGS. 7A and 7B, a horizontal electrode from among the horizontalelectrodes 302.1 through 302.N is driven by an excitation signal whichcapacitively couples to all vertical electrodes 202.1 through 202.M.Specifically, FIG. 7A illustrates capacitive coupling of the drivesignal from horizontal electrode 302.2 and vertical electrode 202.M−1while FIG. 7B illustrates capacitive coupling of the drive signal fromhorizontal electrode 302.2 and vertical electrode 202.M. For explanationpurposes, FIGS. 7A and 7B may be described with elements from previousfigures.

Generally, a mutual capacitance “C_(M)” is associated with each of thehorizontal electrodes 302.1 through 302.N and a corresponding one of thevertical electrodes 202.1 through 202.M. For example, if “i” representsan index for a vertical electrode 202.i from among the verticalelectrodes 202.1 through 202.M, and if “j” represents an index of ahorizontal electrode 302.j from among the horizontal electrodes 302.1through 302.N, then M·N mutual capacitances are present between thevertical electrodes 202.1 through 202.M and the horizontal electrodes302.1 through 302.N, which can be denoted as the set of mutualcapacitances C_(M)(i,j) for i=1 to M and j=1 to N.

FIGS. 2-4, 7A and 7B illustrate only one specific construction andgeometry of electrodes of a PCAP touchscreen. The floating islands arepurely optional. The electrode material may be ITO, a metal mesh, silvernanowires, an intrinsically conductive polymer, or any other conductivematerial. The electrode geometry may include diamond shaped pads (as inFIGS. 2-4, 7A, and 7B) or may simply divide the touch area intorectangular strips. The ideas presented below apply to any PCAPtouchscreen with X and Y electrodes, that is to any touchscreenconstruction with a set of vertically oriented electrodes and with a setof horizontally oriented electrodes and associated self and mutualcapacitances.

FIG. 5 illustrates a conceptual circuit 500 for mutual-capacitancereadout mode, according to example embodiments of the disclosure. Asignal VDRIVE(t) excites horizontal electrode j which couples throughmutual capacitance CM(i,j) to vertical sense electrode which in turn isconnected to a current sensing circuit. The signal output voltageVOUT(t) is proportional to the charge on the integrating capacitorCSENSE. Note that the excitation signal is connected to one electrode(electrode j) and the sensing circuit is connected to another electrode(electrode i) and the measured signal is proportional to the mutualcapacitance CM(i,j). A touch reduces the value of CM(i,j) by an amountΔCM(i,j). In other words, ΔCM(i,j) represents touch induced changes inthe measured mutual capacitance between vertical electrode “i” andhorizontal electrode “j” relative to the baseline values CM(i,j).

FIG. 6 illustrates a schematic representation 600 of a PCAP touchscreen,according to example embodiments of the disclosure. For explanationpurposes, FIG. 6 may be described with elements from previous figures.FIG. 6 is a simplified schematic representation of the PCAP touchscreenof FIG. 7A or 7B. The dashed vertical lines labeled X₁, X₂, X₃, . . .X_(i) . . . X_(M) represent vertical electrodes i=1, 2, 3, . . . M. Thesolid horizontal lines labeled Y₁, Y₂, Y₃, . . . Y_(j) . . . Y_(N)represent horizontal electrodes j=1, 2, 3, . . . N. Each intersection ofa vertical dashed line i and horizontal solid line j represents ameasured mutual capacitance C_(M)(i,j) and measured mutual capacitancechange ΔC_(M)(i,j).

FIG. 8 illustrates a modified schematic representation 800 of a PCAPtouchscreen, according to example embodiments of the disclosure. Forexplanation purposes, FIG. 8 may be described with elements fromprevious figures. FIG. 8 is a modified version of the FIG. 6 in whichsolid circles indicate intersections of electrodes with significantnon-zero values of mutual capacitance change ΔC_(M)(i,j) resulting froma touch. Large circle diameters correspond to larger values ofΔC_(M)(i,j). The touch center is close to the intersection of thevertical electrode labeled X₆ and the horizontal electrode labeled Y₅.The dashed square encloses all electrode intersections (i,j) withmeasurably non-zero values of ΔC_(M)(i,j). As drawn, the dashed squareincludes electrode intersections (i,j) for which i=4, 5, 6, 7 or 8 andfor which j=3, 4, 5, 6 or 7. Letting i_(MIN) and i_(MAX) be the minimumand maximum vertical electrode index values in the neighborhood of thetouch, as drawn, i_(MIN)=4 and i_(MAX)=8. Likewise, letting j_(MIN) andj_(MAX) define the vertical extent of the touch area with the values,j_(MIN)=3 and j_(MAX)=7, as drawn in the sketch. Low-level raw touchsignal data values of ΔC_(M)(i,j) within the touch areai_(MIN)≤i≤i_(MAX) and j_(MIN)≤j≤j_(MAX) may be processed to derivehigh-level (x,y) touch coordinate information for the related touch.

Below are formulas that may be used to process the low-level raw touchsignal data ΔC_(M)(i,j) to produce the high-level touch coordinates(x,y). Note that the resulting high-level information, namely the twonumbers x and y, are highly compressed relative to the correspondinglow-level data ΔC_(M)(i,j), which corresponds to 28 numbers as drawn inFIG. 8.

$x = {\sum\limits_{i = i_{MIN}}^{i_{MAX}}{\sum\limits_{j = j_{MIN}}^{j_{MAX}}{{X_{i} \cdot \Delta}\;{{C_{M}\left( {i,j} \right)}/S}}}}$$y = {\sum\limits_{i = i_{MIN}}^{i_{MAX}}{\sum\limits_{j = j_{MIN}}^{j_{MAX}}{{Y_{j} \cdot \Delta}\;{{C_{M}\left( {i,j} \right)}/S}}}}$$S = {\sum\limits_{i = i_{MIN}}^{i_{MAX}}{\sum\limits_{j = j_{MIN}}^{j_{MAX}}{\Delta\;{C_{M}\left( {i,j} \right)}}}}$

Readout of projected-capacitive touchscreens is done with appropriatecontroller electronics. Typically, controller electronics is in the formof a printed circuit board containing a number of electronic componentsincluding a sophisticated ASIC. The ASIC coordinates drive signals andmeasures the mutual capacitance signals ΔC_(M)(i,j). Particularly forsmall projected-capacitive touchscreens used in mobile devices, a singleASIC contains sufficient circuitry and pins to support all of thetouchscreens M+N electrodes. However, for larger commercialtouchscreens, it is often the case that the controller electronicsincludes multiple ASICs to provide a sufficient number of electronicchannels (e.g., driver and receiver circuits) to support all touchscreenelectrodes.

FIG. 9 illustrates a large PCAP touchscreen 900 with two touchcontroller ASICs requiring challenging inter-ASIC data transfer. Forexplanation purposes, FIG. 9 may be described with elements fromprevious figures. Although FIG. 9 illustrates a case in which two ASICsare used, more than two ASICs are possible. When a first ASIC receivessignals from the vertical electrodes on the left half of the touchscreenand a second ASIC receives signals from the vertical electrodes on theright half of the touchscreen, the first ASIC measures mutualcapacitance signals ΔC_(M)(i,j) for i=1, 2, 3, . . . M/2 while thesecond ASIC measures mutual capacitance signals for i=M/2+1, M/2+2,M/2+3, . . . M. If M is odd, M/2 is replaced by the integer value(M−1)/2, and more generally the touchscreen be divided into left andright portions of unequal size.

The horizontal electrodes are driven sequentially, one at the time. Forexample, the horizontal electrode Y₁ may be excited by driver circuitsin ASIC 1, then Y₂, then Y₃, etc. while ASIC 2 driver circuits are off.After horizontal electrode with j index equal to N/2 has been excited,then the ASIC 1 driver circuits are turned off. After that ASIC 2excites the horizontal electrode with j index equal to (N/2+1), and then(N/2+2), (N/2+3), etc. through to the last horizontal electrode Y_(N).Note that even when one ASIC has its driver circuits off, its receivercircuits may be actively measuring values of C_(M)(i,j) with the aid ofexcitation signals from the other ASIC. To enable one ASIC to makemeasurements with the aid of the other ASIC's excitation drive signals,the timing of the two ASICs are carefully synchronized. This isillustrated in FIG. 9 by synchronizing circuitry in communication withboth ASICs. At a minimum the synchronizing circuitry contains a clock.Optionally the synchronizing circuitry may be complex and include aprogrammable microprocessor (e.g., processor 150 of FIG. 1.)

FIG. 10 illustrates a timing diagram 1000 representative of timingchallenges of a large PCAP touchscreen with inter-ASIC data transferbetween two touch controller ASICs. For explanation purposes, FIG. 10may be described with elements from previous figures. Timing diagram1000 corresponds to activity of the large PCAP touchscreen 900 of FIG.9. Logic trace (a) illustrates a periodic frame trigger pulse thatinitiates measurement and processing of mutual capacitance signalsΔCM(i,j). In the logic traces of timing diagram 1000, a high level islogical “true” and low level is logical “false.”

The time between successive pluses in logic trace (a) is the report rateof the touchscreen system. For example, if the time between successivepulses is 10 millisecond, then the report rate is 100 Hz or one-hundredtouch coordinate reports per second. Typically, applications requirethat the time difference between successive frame trigger pulses beshort compared to human perception times, for example, 10 millisecondsbetween frame trigger pulses. In the example given in the figure, thetime between pulses in logic trace (a) is also an upper limit to thetouch system latency, that is the time between physical contact of afinger touch and reported touch coordinates; however as will bediscussed later, latency limits may differ if touches are reported inthe next frame after the frame in which the touch measurements are made.

As illustrated in logic trace (b), drive signals from ASIC 1 forhorizontal electrodes are initiated by the frame trigger pulse at timeT0 and continues until time T2. At time T2, excitation of the upperhorizontal electrodes is complete, and ASIC 2 begins driving horizontalelectrodes in the lower half of the touchscreen. ASIC 2 generates suchdrive signals between time T2 and T3; see logic trace (c).

As illustrated in logic traces (d) and (e), both ASIC 1 and ASIC 2 arereceiving signals from vertical electrodes and measuring mutualcapacitance signals ΔC_(M)(i,j) the entire time that either ASIC 1 orASIC 2 are generating drive signals for horizontal electrodes.

The ASICs do not need to wait until all data is collected in order toinitiate processing of raw mutual capacitance measurements into touchcoordinates. For example, ASIC 1 has all the information needed tocompute the (x,y) coordinates of touch A illustrated in FIG. 9 after theseventh horizontal electrode has been excited (e.g., Y₇). Likewise ASIC2 can reconstruct the (x,y) coordinates of touch B long before allmutual capacitance values ΔC_(M)(i,j) have been measured. As illustratedin logic traces (g) and (h), the ASICs can start processing touchinformation and computing touch (x,y) coordinates at time T1 shortlyafter commencement of receive signal measurements (e.g., see (d) and(e)). The ASICs can complete calculations of the (x,y) coordinates oftouches A and B in parallel to receive signal measurements. However,touches that overlap the boundary between the left and right halves ofthe touchscreen, such as touch C in FIG. 9, present a special problem.

At the completion of data acquisition at time T3, neither ASIC 1 norASIC 2 have sufficient information to compute the (x,y) coordinates oftouch C. Before raw signal data ΔC_(M)(i,j) can be processed to producethe (x,y) coordinates of touch C, low-level raw touch data are exchangedbetween the two ASICs (or transferred to a third processor forcoordinate calculation). Logic trace (f) illustrates such transfer oflow-level raw touch data between times T3 and T4. After this transfer iscomplete, ASIC1 and ASIC 2 have sufficient information to compute touchcoordinates of all touches on the touchscreen, including those at theboundary between left and right halves of the touchscreen. This isillustrated in logic traces (g) and (h) where touch data processingrecommences and completes between time T4 and time T5.

Finally, between time T5, and the next frame trigger at T6, high-leveltouch information (e.g., final (x,y) touch coordinate information) isreported from one of the touchscreen controller ASIC's (e.g., a mastertouchscreen controller ASIC) or a separate micro-processor unit whichcoordinates the reporting of the final high-level touch information tothe host computer, perhaps after the “touch coordinate trackingalgorithms” further process high-level (x,y) touch coordinateinformation by making use of correlations of touch coordinates betweenframes.

Dealing with touches in the overlap region, such as touch C, reducessystem response time, or adds complexity and cost, increases digitalnoise in touch signal measurements, or a combination of two or all ofthese. Added cost may be in the form of increased product developmenttime and expenses, as well as increased manufacturing costs of theresulting products.

There are several ways in which the response time associated with theabove timing diagram can be improved. If touch reporting (e.g., logictrace (i)) can overlap with mutual capacitance signal measurementsΔC_(M)(i,j) (e.g., logic traces (d) and (e)), then the subsequent frametrigger pulse that initiates of the next cycle of data acquisition maybe moved up from time T6 to time T5 or even T4; while this may improvethe report rate, moving up the subsequent frame trigger pulse does notnecessarily improve the latency of the touchscreen system. If inter-ASICdata transfer (e.g., logic trace (f)) can occur during measurement ofmutual capacitance signals ΔC_(M)(i,j), the timing of the subsequentframe trigger pulse (e.g., logic trace (a)) may be moved earlier to timeT3. However enabling such parallel activity adds to circuit complexityand cost and also increases risk that digital noise will compromise thequality of measurements of mutual capacitance signals ΔC_(M)(i,j).

As described above, multi-ASIC solutions for PCAP systems with largenumbers of electrodes involve engineering trade-offs between responsetime, cost via complexity, and quality of signal measurements. There isdemand for multi-ASIC solutions that minimize the engineeringcompromises made in such trade-offs.

FIG. 11 illustrates a large PCAP touchscreen 1100 with two touchcontroller ASICs with interleaved receiver connections with mutualcapacitance measurements, according to example embodiments of thedisclosure. For explanation purposes, FIG. 11 may be described withelements from previous figures. In some embodiments, connections betweenvertical electrodes and ASIC receiver circuits have been altered.Instead of being connected to the left vertical electrodes with indicesi=1, 2, 3 . . . M/2, ASIC 1 is now connected to vertical electrodes withodd numbered indices i=1, 3, 5 . . . (M−1). Instead of connections tothe right vertical electrodes, ASIC 2 is now connected to verticalelectrodes with even numbered indices i=2, 4, 6 . . . M. This embodimentmay be further reflected in the layout of touch controllerprinted-circuit-board traces on circuit board 140 that connect the ASICpins (e.g., pins associated with receiver circuits) to electrodes oftouchscreen 110 (e.g., the connection may be a connector associated withinterface 160).

By itself, in some cases, the hardware change in touchscreen electrodeto electronic circuit connections of FIG. 11 does little good, and maybe a step backward. To apply the above formulas for calculating (x,y)coordinates, much more data would need to be transferred between the twoASICs. Not only will touch C require data exchange, but touches A and Bwill also require data transfers between the two ASICs. Referring tologic trace (f) of the above timing diagram, a significant increase inthe time interval duration between time T3 and time T4 would be neededto accommodate the greatly increased quantity of data transferred.However, the hardware change of the above figure becomes advantageouswhen combined with additional embodiments described below.

Note that the hardware change involves interleaving of connectionsbetween vertical electrodes and receiver circuits but not betweenhorizontal electrodes and drive circuits. Hence, there is an asymmetrybetween the treatment of receiver circuits and driver circuits. Thisasymmetry results from the fact that receiver circuits capture mutualcapacitance data in parallel, while driver circuit excitations areperformed serially.

In some embodiments, the use of formulas below may eliminate the need totransfer any raw mutual capacitance data ΔC_(M)(i,j) between ASICs.First, the total sum of mutual capacitance signals ΔC_(M)(i,j) (e.g., S)may be split into odd and even partial sums as shown below. One partialsum of index i is over all odd values of i within the rangei_(MIN)≤i≤i_(MAX). The even partial sum is similarly defined. Note thatwhile the calculation of the total sum, S, requires data measured byboth ASICs, the odd partial sum, S_(ODD), may be calculated by ASIC 1without any communication with ASIC 2. Similarly, the even partial sum,S_(EVEN), may be computed by ASIC 2 without any information from ASIC 1:

$S = {{\sum\limits_{i = i_{MIN}}^{i_{MAX}}{\sum\limits_{j = j_{MIN}}^{j_{MAX}}{\Delta\;{C_{M}\left( {i,j} \right)}}}} = {\left\{ {\sum\limits_{i}^{ODD}{\sum\limits_{j = j_{MIN}}^{j_{MAX}}{\Delta\;{C_{M}\left( {i,j} \right)}}}} \right\} + \left\{ {\sum\limits_{i}^{EVEN}{\sum\limits_{j = j_{MIN}}^{j_{MAX}}{\Delta\;{C_{M}\left( {i,j} \right)}}}} \right\}}}$With following definitions, the above equation can be written moreconcisely.

$S_{ODD} \equiv {\sum\limits_{i}^{ODD}{\sum\limits_{j = j_{MIN}}^{j_{MAX}}{\Delta\;{C_{M}\left( {i,j} \right)}}}}$$S_{EVEN} \equiv {\sum\limits_{i}^{EVEN}{\sum\limits_{j = j_{MIN}}^{j_{MAX}}{\Delta\;{C_{M}\left( {i,j} \right)}}}}$

Equation (1) below states that the total sum, S, equals the partialtouch signal measured on odd numbered vertical electrodes, S_(ODD), plusthe partial touch signal measured on even numbered vertical electrodes,S_(EVEN):S=S _(ODD) +S _(EVEN)  (Eq. 1)

The math becomes more complex for the touch coordinates x and y asfollows:

$x = {{\sum\limits_{i = i_{MIN}}^{i_{MAX}}{\sum\limits_{j = j_{MIN}}^{j_{MAX}}{{X_{i} \cdot \Delta}\;{{C_{M}\left( {i,j} \right)}/S}}}} = {\left\{ {\sum\limits_{i}^{ODD}{\sum\limits_{j = j_{MIN}}^{j_{MAX}}{{X_{i} \cdot \Delta}\;{{C_{M}\left( {i,j} \right)}/S}}}} \right\} + \left\{ {\sum\limits_{i}^{EVEN}{\sum\limits_{j = j_{MIN}}^{j_{MAX}}{{X_{i} \cdot \Delta}\;{{C_{M}\left( {i,j} \right)}/S}}}} \right\}}}$$x = {{\frac{S_{ODD}}{S}\left\{ {\sum\limits_{i}^{ODD}{\sum\limits_{j = j_{MIN}}^{j_{MAX}}{{X_{i} \cdot \Delta}\;{{C_{M}\left( {i,j} \right)}/S_{ODD}}}}} \right\}} + {\frac{S_{EVEN}}{S}\left\{ {\sum\limits_{i}^{EVEN}{\sum\limits_{j = j_{MIN}}^{j_{MAX}}{{X_{i} \cdot \Delta}\;{{C_{M}\left( {i,j} \right)}/S_{EVEN}}}}} \right\}}}$

With the following definitions, the above equation can be written moreconcisely. For example, the X_(ODD) coordinate estimated from signals onthe odd vertical electrodes and the X_(EVEN) coordinate estimated fromsignals on the even numbered vertical electrodes may be defined asfollows (where the triple bar “≡” means equality by definition):

$X_{ODD} \equiv {\sum\limits_{i}^{ODD}{\sum\limits_{j = {MIN}}^{j_{MAX}}{{X_{i} \cdot \Delta}\;{{C_{M}\left( {i,j} \right)}/S_{ODD}}}}}$$X_{EVEN} \equiv {\sum\limits_{i}^{EVEN}{\sum\limits_{j = j_{MIN}}^{j_{MAX}}{{X_{i} \cdot \Delta}\;{{C_{M}\left( {i,j} \right)}/S_{EVEN}}}}}$

The concise version of the equation states that a precise value of thetouch coordinate x may be computed as a weighted sum of X_(ODD) andX_(EVEN), the X coordinate estimated from signals on the odd and evennumbered vertical electrodes respectively:

$\begin{matrix}{x = {{\frac{s_{ODD}}{s}X_{ODD}} + {\frac{s_{EVEN}}{s}X_{EVEN}}}} & \left( {{Eq}.\mspace{14mu} 2} \right)\end{matrix}$

While X_(ODD) and X_(EVEN) may be poor estimates of the touchcoordinate, they may be used with the above Equation 2 to provide aprecise estimate of the x touch coordinate.

Odd and even estimates of Y touch coordinates may be similarly definedas follows.

$Y_{ODD} \equiv {\sum\limits_{i}^{ODD}{\sum\limits_{j = j_{MIN}}^{j_{MAX}}{{Y_{i} \cdot \Delta}\;{{C_{M}\left( {i,j} \right)}/S_{ODD}}}}}$$Y_{EVEN} \equiv {\sum\limits_{i}^{EVEN}{\sum\limits_{j = j_{MIN}}^{j_{MAX}}{{Y_{j} \cdot \Delta}\;{{C_{M}\left( {i,j} \right)}/S_{EVEN}}}}}$

Similar as for the x coordinate, Equation 3 below states that a precisevalue of the touch coordinate y may be computed as a weighted sum ofY_(ODD) and Y_(EVEN), the y coordinate estimated from signals on the oddand even numbered vertical electrodes respectively.

$\begin{matrix}{y = {{\frac{s_{ODD}}{s}Y_{ODD}} + {\frac{s_{EVEN}}{s}Y_{EVEN}}}} & \left( {{Eq}.\mspace{14mu} 3} \right)\end{matrix}$

The definitions of X_(ODD) and Y_(ODD) are carefully chosen so that theymay be computed entirely with information contained within ASIC 1 priorto any communication with ASIC 2. Similarly, X_(EVEN) and Y_(EVEN) maybe computed by ASIC 2 with no information from ASIC 1.

To compute (x,y) touch coordinates using Equations 1-3 above, coarsetouch coordinate data (e.g., S_(ODD), X_(ODD), Y_(ODD), S_(EVEN),X_(EVEN), and Y_(EVEN)) may be communicated from respective ASIC 1(e.g., touchscreen controller ASIC 120 a) and ASIC 2 (touchscreencontroller ASIC 120 b) to synchronizing circuitry or processor (e.g.,processor 150). For example, final (x,y) touchscreen coordinates may becomputed and communicated by processor 150 to computing device 130 whenprocessor 150 receives from ASIC 1 (e.g., touchscreen controller ASIC120 a) the three numerical values of S_(ODD), X_(ODD) and Y_(ODD), andthe values of S_(EVEN), X_(EVEN) and Y_(EVEN) from ASIC2 (e.g.,touchscreen controller ASIC 120 b). Note that no raw mutual capacitancedata ΔC_(M)(i,j) need be exchanged between ASICs. Rather, the exchangeof coarse touch coordinate data includes much compressed high-leveltouch information regarding odd or even estimates of touch coordinatesand odd or even signal sums from respective ASICs to a processor (e.g.,processor 150) that can result in the processor determining finaltouchscreen coordinates to be reported to computing device 130. And, thedetermining process may be a linear interpolation or a weightedsummation function.

In the above equations, it was implicitly assumed that the two ASICsagree to common ranges of indices i_(MIN)≤i≤i_(MAX) andj_(MIN)≤j≤j_(MAX) in the neighborhood of each touch before computing oddand even estimates of touch coordinates and odd and even estimates ofsignal sums. Recall that the vertical electrodes are represented by “i”and the horizontal electrodes are represented by “j.” The implicitassumption of the common range of indices requires communication betweenthe ASICs before odd and even touch coordinates can be computed, and isthus undesirable.

Alternative to summing over a square or rectangular region oftouchscreen 110 containing a touch, some embodiments include a summationdetermined over whatever shape the touch has, which may be irregular,for example. FIG. 12 illustrates a portion of a large PCAP touchscreen1200 with two touch controller ASICs with interleaved receiverconnections, according to example embodiments of the disclosure. Forexplanation purposes, FIG. 12 may be described with elements fromprevious figures. Within the neighborhood of a touch, index k indicatesthe number of intersections between vertical and horizontal electrodeswhere the measured mutual capacitance signal ΔC_(M)(i,j) satisfies aconfigurable threshold, such as a significant touch threshold. Thesignificant touch threshold may be chosen to separate significant touchsignals from electronic noise. In FIG. 12, solid and open circlescorrespond to electrode intersections with signals that satisfy thesignificant touch threshold (e.g., satisfy may mean greater than orgreater than or equal to). Let K be the number of electrodeintersections with measured mutual capacitance signals above thesignificant touch threshold. In the example illustrated in FIG. 12, Kequals 14. Furthermore, let K_(ODD) be the number of electrodeintersections above threshold in which the vertical electrode number isodd. Let K_(EVEN) be defined similarly so that K=K_(ODD)+K_(EVEN). Inthe illustrated example, both K_(ODD) and K_(EVEN) equal seven.

In FIG. 12, signals measured on odd numbered vertical electrodes thatsatisfy the significant touch threshold are represented by solid circlesand signals measured on even vertical electrodes by unfilled circles. Asnumbered in the above figure, signals for k=1, 2, 3, . . . 7 which makeup K_(ODD) are from odd numbered vertical electrodes and signals fork=(K_(ODD)+1)=8, 9, 10 . . . 14 which make up K_(EVEN) are from evennumbered vertical electrodes.

Some embodiments replace the two-dimensional sum over electrode indicesi and j with a single sum over k. That is, instead of summing over asquare or rectangular region containing the touch, the sum is overwhatever irregular shape the touch may have. For any intersection indexk, that horizontal and vertical indices i and j are determined by theintersection location. In this sense, i and j are functions of index kand may be notated as i(k) and j(k). With this notation, it is possibleto calculate the touch signal sum and (x,y) coordinates using thefollowing equations involving a single sum over k, rather than twodimensional sums (e.g., double sums) over i and j.

$S = {\sum\limits_{k = 1}^{K}{\Delta\;{C_{M}\left( {{i(k)},{j(k)}} \right)}}}$$x = {\sum\limits_{k = 1}^{K}{{X_{i{(k)}} \cdot \Delta}\;{{C_{M}\left( {{i(k)},{j(k)}} \right)}/S}}}$$y = {\sum\limits_{k = 1}^{K}{{Y_{j{(k)}} \cdot \Delta}\;{{C_{M}\left( {{i(k)},{j(k)}} \right)}/S}}}$

Similarly, the odd and even versions of coordinate estimates and partialsignal sums may be redefined as follows, where the modified index k′ forthe alternate expressions for X_(EVEN) and Y_(EVEN) is defined by theequation k′=k−K_(ODD).

$S_{ODD} \equiv {\sum\limits_{k = 1}^{K_{ODD}}{\Delta\;{C_{M}\left( {{i(k)},{j(k)}} \right)}}}$$S_{EVEN} \equiv {\sum\limits_{k = {K_{ODD} + 1}}^{K}{\Delta\;{C_{M}\left( {{i(k)},{j(k)}} \right)}}}$$S_{EVEN} = {\sum\limits_{k^{\prime} = 1}^{K_{EVEN}}{\Delta\;{C_{M}\left( {{i\left( k^{\prime} \right)},{j\left( k^{\prime} \right)}} \right)}}}$$X_{ODD} \equiv {\sum\limits_{k = 1}^{K_{ODD}}{{X_{i{(k)}} \cdot \Delta}\;{{C_{M}\left( {{i(k)},{j(k)}} \right)}/S_{ODD}}}}$$X_{EVEN} \equiv {\sum\limits_{k = {K_{ODD} + 1}}^{K}{{X_{i{(k)}} \cdot \Delta}\;{{C_{M}\left( {{i(k)},{j(k)}} \right)}/S_{EVEN}}}}$$X_{EVEN} = {\sum\limits_{k^{\prime} = 1}^{K_{EVEN}}{{X_{i{(k^{\prime})}} \cdot \Delta}\;{{C_{M}\left( {{i\left( k^{\prime} \right)},{j\left( k^{\prime} \right)}} \right)}/S_{EVEN}}}}$$Y_{ODD} \equiv {\sum\limits_{k = 1}^{K_{ODD}}{{Y_{j{(k)}} \cdot \Delta}\;{{C_{M}\left( {{i(k)},{j(k)}} \right)}/S_{ODD}}}}$$Y_{EVEN} \equiv {\sum\limits_{k = {K_{ODD} + 1}}^{K}{{Y_{j{(k)}} \cdot \Delta}\;{{C_{M}\left( {{i(k)},{j(k)}} \right)}/S_{EVEN}}}}$$Y_{EVEN} = {\sum\limits_{k^{\prime} = 1}^{K_{EVEN}}{{Y_{j{(k^{\prime})}} \cdot \Delta}\;{{C_{M}\left( {{i\left( k^{\prime} \right)},{j\left( k^{\prime} \right)}} \right)}/S_{EVEN}}}}$

It can be mathematically proven (but not shown here) that the aboveequations lead to the equations below.

$x = {{\frac{S_{ODD}}{S}X_{ODD}} + {\frac{S_{EVEN}}{S}X_{EVEN}}}$$y = {{\frac{S_{ODD}}{S}Y_{ODD}} + {\frac{S_{EVEN}}{S}Y_{EVEN}}}$

These equations look exactly the same as equations derived above.However, there is a big difference. In some embodiments, S_(ODD),X_(ODD) and Y_(ODD) may be computed by ASIC 1 (using the index k) over asmaller area of touchscreen 110 and still with no information from ASIC2. Likewise, S_(EVEN), X_(EVEN) and Y_(EVEN) may be computed (using thealternative index k′) by ASIC 2 over a smaller area of touchscreen 110and still with no information from ASIC 1.

FIG. 13 illustrates a timing diagram 1300 of a large PCAP touchscreenwith two touch controller ASICs with interleaved receiver connections,according to example embodiments of the disclosure. For explanationpurposes, FIG. 13 may be described with elements from previous figures.FIG. 13 demonstrates the advantages of the embodiments described above.The inter-ASIC data transfer (f) of FIG. 10 has been eliminated, as itis no longer necessary. The amount of calculation to combine touchcoordinate information from the two ASICs is negligible and can beincluded as part of the touch reporting (i) with negligible delays. Thisallows a faster time response as indicated by the arrow in logic trace(a), without significantly added complexity or cost, and without anyadded digital noise.

Similar methods may be applied to touchscreen systems with three or moreASICs. FIG. 14 illustrates a large PCAP touchscreen 1400 with four touchcontroller ASICs with interleaved receiver connections, according toexample embodiments of the disclosure. For explanation purposes, FIG. 14may be described with elements from previous figures. The coarse touchcoordinates data (e.g., high-level touch information) determined by eachof the four ASICs of FIG. 14 may be combined as shown in the equationsbelow:

$x = {{\frac{S_{FIRST}}{S}X_{FIRST}} + {\frac{S_{SECOND}}{S}X_{SECOND}} + {\frac{S_{THIRD}}{S}X_{THIRD}} + {\frac{S_{FOURTH}}{S}X_{FOURTH}}}$$y = {{\frac{S_{FIRST}}{S}Y_{FIRST}} + {\frac{S_{SECOND}}{S}Y_{SECOND}} + {\frac{S_{THIRD}}{S}Y_{THIRD}} + {\frac{S_{FOURTH}}{S}Y_{FOURTH}}}$

In the above equations, the total signal sum and ASIC partial signalsums are as follows where K_(FIRST), K_(SECOND), K_(THIRD) andK_(FOURTH) are the number of mutual capacitance signals ΔC_(M)(i,j) thatsatisfy a significant touch threshold measured by each correspondingASIC for a touch. For the second, third and fourth ASIC signal partialsums, k′=k−K_(FIRST), k″=k′−K_(SECOND), and k′″=k″−K_(THIRD) are thecorresponding indices.

$S = {\sum\limits_{k = 1}^{K}{\Delta\;{C_{M}\left( {{i(k)},{j(k)}} \right)}}}$$S_{FIRST} \equiv {\sum\limits_{k = 1}^{K_{FIRST}}{\Delta\;{C_{M}\left( {{i(k)},{j(k)}} \right)}}}$$\begin{matrix}{S_{SECOND} \equiv {\sum\limits_{k = {K_{FIRST} + 1}}^{K_{FIRST} + K_{SECOND}}{\Delta\;{C_{M}\left( {{i(k)},{j(k)}} \right)}}}} \\{= {\sum\limits_{k^{\prime} = 1}^{K_{SECOND}}{\Delta\;{C_{M}\left( {{i\left( k^{\prime} \right)},{j\left( k^{\prime} \right)}} \right)}}}}\end{matrix}$ $\begin{matrix}{S_{THIRD} \equiv {\sum\limits_{k = {K_{FIRST} + K_{SECOND} + 1}}^{K_{FIRST} + K_{SECOND} + K_{THIRD}}{\Delta\;{C_{M}\left( {{i(k)},{j(k)}} \right)}}}} \\{= {\sum\limits_{k^{''} = 1}^{K_{THIRD}}{\Delta\;{C_{M}\left( {{i\left( k^{''} \right)},{j\left( k^{''} \right)}} \right)}}}}\end{matrix}$ $\begin{matrix}{S_{FOURTH} \equiv {\sum\limits_{k = {K_{FIRST} + K_{SECOND} + K_{THIRD} + 1}}^{K_{FIRST} + K_{SECOND} + K_{THIRD} + K_{FOURTH}}{\Delta\;{C_{M}\left( {{i(k)},{j(k)}} \right)}}}} \\{= {\sum\limits_{k^{\prime\prime\prime} = 1}^{K_{FOURTH}}{\Delta\;{C_{M}\left( {{i\left( k^{\prime\prime\prime} \right)},{j\left( k^{\prime\prime\prime} \right)}} \right)}}}}\end{matrix}$

Below are formulas for touch coordinate estimates of each ASIC:

$X_{FIRST} = {\sum\limits_{k = 1}^{K_{FIRST}}{{X_{i{(k)}} \cdot \Delta}\;{{C_{M}\left( {{i(k)},{j(k)}} \right)}/S_{FIRST}}}}$$Y_{FIRST} = {\sum\limits_{k = 1}^{K_{FIRST}}{{Y_{j{(k)}} \cdot \Delta}\;{{C_{M}\left( {{i(k)},{j(k)}} \right)}/S_{FIRST}}}}$$X_{SECOND} = {\sum\limits_{k^{\prime} = 1}^{K_{SECOND}}{{X_{i{(k^{\prime})}} \cdot \Delta}\;{{C_{M}\left( {{i\left( k^{\prime} \right)},{j\left( k^{\prime} \right)}} \right)}/S_{SECOND}}}}$$Y_{SECOND} = {\sum\limits_{k^{\prime} = 1}^{K_{SECOND}}{{Y_{j{(k^{\prime})}} \cdot \Delta}\;{{C_{M}\left( {{i\left( k^{\prime} \right)},{j\left( k^{\prime} \right)}} \right)}/S_{SECOND}}}}$$X_{THIRD} = {\sum\limits_{k^{''} = 1}^{K_{THIRD}}{{X_{i{(k^{''})}} \cdot \Delta}\;{{C_{M}\left( {{i\left( k^{''} \right)},{j\left( k^{''} \right)}} \right)}/S_{THIRD}}}}$$Y_{THIRD} = {\sum\limits_{k^{''} = 1}^{K_{THIRD}}{{Y_{j{(k^{''})}} \cdot \Delta}\;{{C_{M}\left( {{i\left( k^{''} \right)},{j\left( k^{''} \right)}} \right)}/S_{THIRD}}}}$$X_{FOURTH} = {\sum\limits_{k^{\prime\prime\prime} = 1}^{K_{FOURTH}}{{X_{i{(k^{\prime\prime\prime})}} \cdot \Delta}\;{{C_{M}\left( {{i\left( k^{\prime\prime\prime} \right)},{j\left( k^{\prime\prime\prime} \right)}} \right)}/S_{FOURTH}}}}$$Y_{FOURTH} = {\sum\limits_{k^{\prime\prime\prime} = 1}^{K_{FOURTH}}{{Y_{j{(k^{\prime\prime\prime})}} \cdot \Delta}\;{{C_{M}\left( {{i\left( k^{\prime\prime\prime} \right)},{j\left( k^{\prime\prime\prime} \right)}} \right)}/S_{FOURTH}}}}$

With the above examples for two and four ASICs, corresponding formulasfor other numbers of ASICs, such a three ASICs, may be determined.

Pitch size is the distance between two neighboring electrodes on thelarge PCAP touchscreen, and a common pitch size is 5 mm-7 mm. In theexample of a PCAP touch system using two touch controller ASICs withinterleaved connections of the receiver circuits, the coarse touchcoordinate data (e.g., S_(ODD), X_(ODD) and Y_(ODD)) may be determinedfrom an effective pitch size that is twice as large as the originalpitch size of the touch screen. Accordingly, when the number of multipleASICs used is N, each ASIC of the N ASICs processes raw touch data froma subgroup of electrodes that span the large PCAP touchscreen in thereceiver dimension with a coarser pitch size than the original pitchsize to produce a subset of the coarse touch coordinates data. Thecoarser pitch size may be equal to N*(Original_Pitch) size. Originalpitch sizes less than 7.5 mm are desired in the receiver dimension forN=2, as the coarser pitch size seen by each of the N=2 ASIC's may be upto 15 mm in the receiver dimension.

The above embodiments may be applied to mixed mutual-mode and self-modefor increased water immunity as described in the Immunity Application.For the purpose of improving touch performance in the presence of watercontaminants, it is useful to measure both self-capacitances and mutualcapacitances. In brief, self-capacitance measurements are lesssusceptible to the effects of water contamination on the touch surface,while mutual-capacitance measurements provide better multiple touchperformance, and mixed mode systems combine the strengths of both.

The nature of mutual capacitance measurements has been described above.Self capacitances C^(V) _(S)(i) are associated with vertical electrodesof index i where i=1, 2, 3, . . . M and self capacitances C^(H) _(S)(j)are associated with horizontal electrodes of index j where j=1, 2, 3, .. . N. FIG. 15 illustrates a conceptual circuit 1500 forself-capacitance readout mode, according to example embodiments of thedisclosure. For explanation purposes, FIG. 15 may be described withelements from previous figures. A signal V_(DRIVE)(t) at the positivehigh-gain differential amplifier input, is via feedback reproduced atthe negative differential amplifier input, which in turn drives oneelectrode (vertical electrode i or horizontal electrode j). The groundto the left of the electrode self-capacitance C^(V) _(S)(i) or C^(H)_(S)(j) includes stray capacitances from the electrode to ground, aswell as the grounding effect of any finger touch. A touch increases thevalue of C^(V) _(S)(i) or C^(H) _(S)(j). The charge on integratingcapacitor C_(SENSE) is the same as the charge on C^(V) _(S)(i) or C^(H)_(S)(j), and hence the signal output voltage V_(OUT)(t) is proportionalto the charge in C^(V) _(S)(i) or C^(H) _(S)(j). Note that in self-modethe excitation signal is delivered to the same electrode (i or j) thatis sensed.

In the determination of the location of a touch using self-capacitancemeasurements, the X coordinate of the touch is determined fromself-capacitances C^(V) _(S)(i) of vertical electrodes and the Ycoordinate is determined from the self-capacitances C^(H) _(S)(j) ofhorizontal electrodes. Hence self-capacitances C^(V) _(S)(i) and C^(H)_(S)(j) of both vertical and horizontal electrodes are needed todetermine the two-dimensional (x,y) coordinates of a touch. FIG. 16illustrates an example 1600 of self-capacitance touch measurements,according to example embodiments of the disclosure. To determine thelocation of touch A at the intersection of vertical electrode of index iand the horizontal electrode of index j, data from both vertical andhorizontal electrodes is required. If data is available only fromvertical electrodes, then one cannot determine if the touch is at pointA, or at point B, or at some other point along vertical electrode i.Likewise, if only horizontal electrode data is available, then onecannot determine if the touch is at point A, or at point C, or at someother point along horizontal electrode j.

The next three figures analyze what self-capacitance data is availableto each of two ASICs for three different interconnect options.Interleaved connections are not only advantageous for mutual-mode asdescribed above, but also advantageous for self-mode as explained below.

FIG. 17 illustrates a large PCAP touchscreen 1700 with inter-ASIC datatransfer between two touch controller ASICs. FIG. 17 is the same as FIG.9, except for the solid and dashed rectangles superposed on thetouchscreen area. The upper left solid rectangle corresponds to theportion of the touchscreen area for which ASIC 1 generates both verticaland horizontal self-capacitance data and hence can compute (x,y) touchcoordinates from self-mode data with no data from ASIC 2. Similarly, thelower right solid rectangle outlines the touch area where ASIC 2 candetermine touch coordinates with no help from ASIC 1. In these twoportions of the touchscreen surface, a single ASIC can collect bothmutual-mode and self-mode data and flag candidate touches, as eitherconvincing or suspect in the presence of water contamination. However,the other two quadrants of the touch area are problematic. For the lowerleft quadrant, ASIC 1 only has X coordinate information forself-capacitance measurements and ASIC 2 only has Y information forself-capacitance measurements. For the upper right quadrant, ASIC 1 onlyhas Y coordinate information for self-capacitance measurements and ASIC2 only has X information for self-capacitance measurements. Without dataexchange between ASICs, water rejection algorithms will be lesseffective in the lower left and upper right quadrants. With dataexchange between ASICs, the above discussed disadvantages of complexity,cost and noise exist.

FIG. 18 illustrates a large PCAP touchscreen using two touch controllerASICs with interleaved receiver connections with self capacitancemeasurements, according to example embodiments of the disclosure. Forexplanation purposes, FIG. 18 may be described with elements fromprevious figures. FIG. 18 is the same as FIG. 11, except for the solidrectangles superposed on the touchscreen area. The upper solid rectanglecorresponds to the portion of the touchscreen area for which ASIC 1generates both vertical and horizontal self-capacitance data (exceptthat the measurements for vertical self-capacitance is coarse) and hencecan compute (x,y) touch coordinates from self-mode data (except that Xtouch coordinate estimate is coarse) with no data from ASIC 2.Similarly, the lower solid rectangle outlines the touch area where ASIC2 can determine touch coordinates with no help from ASIC 1 (except thatX touch coordinate estimate is coarse). These two portions of thetouchscreen surface cover the entire touch area, thus avoiding theundesirable situation above in which some areas generate only onecoordinate for self-capacitance measurements in either ASIC. While eachASIC samples every-other vertical electrode, this is much preferable tomissing one coordinate entirely for half the touch area. Thus,interleaved connections are advantages not only for mutual-mode, butalso for self-mode.

FIG. 19 illustrates a large PCAP touchscreen 1900 using two touchcontroller ASICs with interleaved receiver connections and interleaveddriver connections, according to example embodiments of the disclosure.For explanation purposes, FIG. 19 may be described with elements fromprevious figures. While adding interleaving driver connections providesno advantage for mutual-mode, for self-mode, interleaved receiverconnections and interleaved driver connections provide a furtheradvantage of allowing both ASIC 1 and ASIC 2 to generate coarse X and Yself-capacitance data over the entire touch area of large PCAPtouchscreen 1900.

FIG. 20 illustrates a timing diagram 2000 of a large PCAP touchscreenusing two touch controller ASICs with interleaved receiver connectionsand interleaved driver connections, according to example embodiments ofthe disclosure. Timing diagram 2000 is similar to timing diagram 1300for mutual-mode with interleaved receiver connections. Logic traces (a)through (i) have the same meanings as in timing diagram 1300. Timingdiagram 2000 has an additional logic trace (j) with a high or logic truestate between times T0 and T8. During this time self-mode measurementare made. Initiation of mutual-mode measurements are delayed from timeT0 to time T8. Optionally self-mode measurements are collected at a highand low frequency as described in the Immunity Application. As shown,self-mode measurements precede mutual-mode measurements, but optionallythis order may be reversed. As noted above, interleaved connectionsenable a reduction of the time required to make mutual-modemeasurements, thus supporting mixed-mode designs by allowing more roomin the timing budget for self-mode measurements.

Various embodiments can be implemented, for example, using one or morewell-known computer systems, such as computer system 2100 shown in FIG.21. Computer system 2100 can be any well-known computer capable ofperforming the functions described herein such as computing device 130and circuit board 140. Computer system 2100 may be internal or externalto system 100 as discussed above.

Computer system 2100 includes one or more processors (also calledcentral processing units, or CPUs), such as a processor 2104. Processor2104 is connected to a communication infrastructure or bus 2106. One ormore processors 2104 may each be a graphics processing unit (GPU). In anembodiment, a GPU is a processor that is a specialized electroniccircuit designed to process mathematically intensive applications. TheGPU may have a parallel structure that is efficient for parallelprocessing of large blocks of data, such as mathematically intensivedata common to computer graphics applications, images, videos, etc.Computer system 2100 also includes user input/output device(s) 2102,such as monitors, keyboards, pointing devices, etc., that communicatewith communication infrastructure 2106 through user input/outputinterface(s) 2102.

Computer system 2100 also includes a main or primary memory 2108, suchas random access memory (RAM). Main memory 2108 may include one or morelevels of cache. Main memory 2108 has stored therein control logic(i.e., computer software) and/or data. Computer system 2100 may alsoinclude one or more secondary storage devices or memory 2110. Secondarymemory 2110 may include, for example, a hard disk drive 2112 and/or aremovable storage device or drive 2114. Removable storage drive 2114 maybe a floppy disk drive, a magnetic tape drive, a compact disk drive, anoptical storage device, tape backup device, and/or any other storagedevice/drive.

Removable storage drive 2114 may interact with a removable storage unit2118. Removable storage unit 2118 includes a computer usable or readablestorage device having stored thereon computer software (control logic)and/or data. Removable storage unit 2118 may be a floppy disk, magnetictape, compact disk, DVD, optical storage disk, and/any other computerdata storage device. Removable storage drive 414 reads from and/orwrites to removable storage unit 2118 in a well-known manner.

According to an exemplary embodiment, secondary memory 2110 may includeother means, instrumentalities or other approaches for allowing computerprograms and/or other instructions and/or data to be accessed bycomputer system 2100. Such means, instrumentalities or other approachesmay include, for example, a removable storage unit 2122 and an interface2120. Examples of the removable storage unit 2122 and the interface 2120may include a program cartridge and cartridge interface (such as thatfound in video game devices), a removable memory chip (such as an EPROMor PROM) and associated socket, a memory stick and USB port, a memorycard and associated memory card slot, and/or any other removable storageunit and associated interface.

Computer system 2100 may further include a communication or networkinterface 2124. Communication interface 2124 enables computer system2100 to communicate and interact with any combination of remote devices,remote networks, remote entities, etc. (individually and collectivelyreferenced by reference number 2128). For example, communicationinterface 2124 may allow computer system 2100 to communicate with remotedevices 2128 over communications path 2126, which may be wired and/orwireless, and which may include any combination of LANs, WANs, theInternet, etc. Control logic and/or data may be transmitted to and fromcomputer system 2100 via communication path 2126.

In an embodiment, a tangible apparatus or article of manufacturecomprising a tangible computer useable or readable medium having controllogic (software) stored thereon is also referred to herein as a computerprogram product or program storage device. This includes, but is notlimited to, computer system 2100, main memory 2108, secondary memory2110, and removable storage units 2118 and 2122, as well as tangiblearticles of manufacture embodying any combination of the foregoing. Suchcontrol logic, when executed by one or more data processing devices(such as computer system 2100), causes such data processing devices tooperate as described herein.

The foregoing description, for purposes of explanation, used specificnomenclature to provide a thorough understanding of the disclosure.However, it will be apparent to one skilled in the art that specificdetails are not required in order to practice the disclosure. Thus, theforegoing descriptions of specific embodiments of the disclosure arepresented for purposes of illustration and description. They are notintended to be exhaustive or to limit the disclosure to the preciseforms disclosed; obviously, many modifications and variations arepossible in view of the above teachings. The embodiments were chosen anddescribed in order to best explain the principles of the disclosure andits practical applications, they thereby enable others skilled in theart to best utilize the disclosure and various embodiments with variousmodifications as are suited to the particular use contemplated. It isintended that the following claims and their equivalents define thescope of the disclosure.

Based on the teachings contained in this disclosure, it will be apparentto persons skilled in the relevant art(s) how to make and useembodiments of the disclosure using data processing devices, computersystems and/or computer architectures other than that shown in FIG. 21.In particular, embodiments may operate with software, hardware, and/oroperating system implementations other than those described herein.

It is to be appreciated that the Detailed Description section, and notthe Abstract section, is intended to be used to interpret the claims.The Abstract section may set forth one or more, but not all exemplaryembodiments, of the disclosure, and thus, are not intended to limit thedisclosure and the appended claims in any way.

The disclosure has been described above with the aid of functionalbuilding blocks illustrating the implementation of specified functionsand relationships thereof. The boundaries of these functional buildingblocks have been arbitrarily defined herein for the convenience of thedescription. Alternate boundaries may be defined so long as thespecified functions and relationships thereof are appropriatelyperformed.

It will be apparent to those skilled in the relevant art(s) that variouschanges in form and detail can be made therein without departing fromthe spirit and scope of the disclosure. Thus the disclosure should notbe limited by any of the above-described exemplary embodiments. Further,the claims should be defined only in accordance with their recitationsand their equivalents.

What is claimed is:
 1. A projected capacitive (PCAP) touch systemcomprising: a touchscreen; and a first and a second touch controllerapplication-specific integrated circuit (ASIC) communicatively coupledto the touchscreen to detect self-capacitive touch data from touchscreenelectrodes over an entire touch area of the touchscreen, wherein a firstdriver circuit of the first touch controller ASIC comprises firstconnections to a first subset of the touchscreen electrodes, wherein asecond driver circuit of the second touch controller ASIC comprisessecond connections to a second subset of the touchscreen electrodes,wherein the first subset of the touchscreen electrodes is interleavedwith the second subset of the touchscreen electrodes.
 2. The PCAP touchsystem of claim 1, wherein the first and the second touch controllerASICs do not exchange raw self-capacitance data during a measurementframe.
 3. The PCAP touch system of claim 1, wherein the first and thesecond touch controller ASICs generate coarse X and Y self-capacitancedata over the entire touch area of the touchscreen.
 4. The PCAP touchsystem of claim 1, further comprising one or more processors coupled tothe first and the second touch controller ASICs, wherein the one or moreprocessors are configured to: determine a final touch coordinate basedon coarse touch coordinate data from the first and the second touchcontroller ASICs.
 5. The PCAP touch system of claim 4, wherein the firstsubset of the touchscreen electrodes is odd numbered and the secondsubset of touchscreen electrodes is even numbered.
 6. The PCAP touchsystem of claim 4, wherein first coarse touch coordinate data from thefirst touch controller ASIC of the coarse touch coordinate data, isbased on a pitch size of the touchscreen and a sum of a number of thefirst and the second touch controller ASICs.
 7. The PCAP touch system ofclaim 4, wherein the first touch controller ASIC is configured tocalculate first coarse touch coordinate data comprising: a partial sumof mutual capacitance measurements satisfying a significant touchthreshold across a third subset of touchscreen electrodes of thetouchscreen; an X touch coordinate associated with the third subset oftouchscreen electrodes; and a Y touch coordinate associated with thethird subset of touchscreen electrodes, wherein the partial sum, the Xtouch coordinate, and the Y touch coordinate are calculated by the firsttouch controller ASIC without communicating with the second touchcontroller ASIC.
 8. The PCAP touch system of claim 7, wherein thirdconnections between the first touch controller ASIC and the third subsetof touchscreen electrodes of the touchscreen, are interleaved withfourth connections, wherein the fourth connections are between thesecond touch controller ASIC and a fourth subset of touchscreenelectrodes of the touchscreen.
 9. The PCAP touch system of claim 8,wherein first coarse touch coordinate data from the first touchcontroller ASIC of the coarse touch coordinate data, is based at leaston a number of horizontal and vertical electrode intersections of thethird subset of the touchscreen electrodes whose mutual capacitancemeasurements satisfy the significant touch threshold.
 10. The PCAP touchsystem of claim 9, wherein the mutual capacitance measurements aredelayed until after self-capacitance measurements are made.
 11. The PCAPtouch system of claim 9, wherein self-capacitance measurements aredelayed until after the mutual capacitance measurements are made.
 12. Amethod, for a first touch controller application-specific integratedcircuit (ASIC), comprising: determining a first subset of coarse touchcoordinate data received from first driver circuits coupled to a firstsubset of touchscreen electrodes of a projected capacitive (PCAP)touchscreen, wherein the first subset of touchscreen electrodes isinterleaved with a second subset of touchscreen electrodes, wherein thesecond subset of touchscreen electrodes is coupled to second drivercircuits of a second touch controller ASIC, and wherein the first subsetof touchscreen electrodes and the second subset of touchscreenelectrodes together cover an entire touch area of the PCAP touchscreen;and transmitting the first subset of coarse touch coordinate data to aprocessor, wherein the processor receives a second subset of coarsetouch coordinate data from the second touch controller ASIC, and whereinthe processor determines final touch coordinates based on the firstsubset of coarse touch coordinate data and the second subset of coarsetouch coordinate data.
 13. The method of claim 12, wherein the first andthe second touch controller ASICs do not exchange raw mutual capacitanceor self-capacitance data during a measurement frame.
 14. The method ofclaim 12, wherein the first subset of coarse touch coordinate datacomprises coarse X and Y self-capacitance data.
 15. The method of claim12, wherein a coarse pitch size of the first subset of coarse touchcoordinate data from the first touch controller ASIC is based on a pitchsize of the PCAP touchscreen and a sum of a number of the first and thesecond touch controller ASICs.
 16. The method of claim 12, wherein thefirst subset of touchscreen electrodes of the PCAP touchscreen is oddnumbered and the second subset of touchscreen electrodes is evennumbered.
 17. The method of claim 12, wherein the first subset of coarsetouch coordinate data comprises: a partial sum of mutual capacitancemeasurements satisfying a significant touch threshold across a thirdsubset of touchscreen electrodes of the PCAP touchscreen; an X touchcoordinate associated with the third subset of touchscreen electrodes;and a Y touch coordinate associated with the third subset of touchscreenelectrodes, and wherein the determining a first subset of coarse touchcoordinate data is performed without communicating with the second touchcontroller ASIC.
 18. The method of claim 17, wherein first connectionsbetween the first touch controller ASIC and a third subset oftouchscreen electrodes of the PCAP touchscreen, are interleaved withsecond connections, wherein the second connections are between thesecond touch controller ASIC and a fourth subset of touchscreenelectrodes of the PCAP touchscreen.
 19. The method of claim 18, whereinthe first subset of touchscreen electrodes is substantiallyperpendicular to the third subset of touchscreen electrodes.
 20. Anon-transitory computer readable medium having stored therein one ormore instructions that, when executed by one or more processors, causethe one or more processors of a first touch controllerapplication-specific integrated circuit (ASIC) to perform operations,the operations comprising: determining a first subset of coarse touchcoordinate data received from first driver circuits coupled to a firstsubset of touchscreen electrodes of a projected capacitive (PCAP)touchscreen, wherein the first subset of touchscreen electrodes isinterleaved with a second subset of touchscreen electrodes, wherein thesecond subset of touchscreen electrodes is coupled to second drivercircuits of a second touch controller ASIC, wherein the first subset oftouchscreen electrodes and the second subset of touchscreen electrodestogether cover an entire touch area of the PCAP touchscreen; andtransmitting the first subset of coarse touch coordinate data to aprocessor, wherein the processor receives a second subset of coarsetouch coordinate data from the second touch controller ASIC, and whereinthe processor determines final touch coordinates based on the firstsubset of coarse touch coordinate data and the second subset of coarsetouch coordinate data.